The Arabian Peninsula is one of the world’s driest places, hence understanding how climate change may alter local rainfall patterns is critical. According to data comparisons, changes in winter rainfall over the peninsula throughout the 1980s have now been connected to an ocean-atmospheric phenomenon affecting sea surface temperatures in the central Pacific and westerly jet streams arriving from North Africa.
The findings may aid in improving the region’s long-term rainfall forecasts.
About 75% of the peninsula’s rainfall occurs during winter with marked spatial variation, and the total rainfall is relatively very little. This meager rainfall is critically important for local agriculture, drinking water, and ecosystems. We wanted to investigate the long-term changes in winter rainfall patterns across the peninsula and understand how they might be associated with climate phenomena.
Hari Dasari, Research Scientist, King Abdullah University of Science and Technology
Ibrahim Hoteit, an expert in earth modeling, led a team of KAUST researchers in quantifying variations in winter rainfall over the Arabian Peninsula in recent years. They used rainfall data of the region from the University of East Anglia’s Climate Research Unit, as well as observations from 39 stations across the peninsula from 1951 to 2010.
Since 1981, researchers discovered a 25–30% increase in winter rainfall over the eastern Arabian Peninsula, with a 10–20% decline in the south and northeast.
The researchers subsequently examined global climate patterns and discovered that since the mid-1970s, these winter rainfall shifts have been linked to a fluctuating El Niño pattern in the tropical Pacific Ocean.
In the central tropical Pacific, sea surface temperatures increased, with cooler seas on either side. Prior to this time, sea surface temperatures in the eastern Pacific were warmer and those in the western Pacific were cooler. The alteration resulted in a southward shift in the westerly winds — 8–10 km above Earth — which are responsible for guiding low-pressure systems that affect rainfall in the region.
El Niños are the best predicted climate drivers on the interannual scale, often with lead times of 12 months or more. If climate models can capture the observed changes in the links between Indo-Pacific sea surface temperatures and Arabian Peninsula winter rainfall, they could help us predict variations in regional rainfall, with significant implications for sectors like agriculture and tourism.
Ibrahim Hoteit, King Abdullah University of Science and Technology
The team will strive to advance its understanding of the ocean-atmospheric causes of high rainfall and heat events to investigate their implications for future survival.
Dasari, H. P., et al. (2021) Long-term changes in the Arabian Peninsula rainfall and their relationship with the ENSO signals in the tropical Indo-Pacific. Climate Dynamics. doi.org/10.1007/s00382-021-06062-7.